Two years later... Upstream has now offered some thoughts. Although I don't think this bug is around any more(?)
https://bugs.freedesktop.org/show_bug.cgi?id=86366 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to mesa in Ubuntu. https://bugs.launchpad.net/bugs/1377872 Title: Double-buffered compositing performance is sometimes very poor (30 FPS) on intel Status in Mesa: Confirmed Status in Mir: Incomplete Status in mesa package in Ubuntu: Incomplete Bug description: Double-buffered compositing performance is sometimes artificially poor on some intel systems. When this happens the frame rate seen is halved - about 30 FPS. However at the same time, Mir is observed to use very little render time and both the CPU and GPU are still mostly idle. It's just the Intel DRM logic sometimes takes two frames (~32ms) to complete a single page flip. Two known workarounds avoid the issue: (a) Add glFinish() into the mesa DisplayBuffer code; or (b) env INTEL_DEBUG=sync for the Mir server binary. To manage notifications about this bug go to: https://bugs.launchpad.net/mesa/+bug/1377872/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
